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Smallest prime of the form: one or more 4's followed by prime(n) (or 0 if no such prime exists).
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%I #15 May 20 2019 02:49:48

%S 0,43,0,47,44444444444444411,44444444413,44417,419,4423,4444444429,

%T 431,444444437,4441,443,4447,44453,44444459,461,467,4444471,444473,

%U 479,4483,44444489,44497,44101,444444103,444444444444107,444109,444113,4127

%N Smallest prime of the form: one or more 4's followed by prime(n) (or 0 if no such prime exists).

%C Prime(n) is all 0's followed by prime(n). a(n) is all 4's followed by prime(n). Conjecture: No term is zero for n > 3.

%C a(346) = 0 or a(346) > 5000, but note a(892) = 3612. - _D. S. McNeil_, Feb 04 2011

%e a(7) = 44417, as prime(7) = 17 and both 417 and 4417 are composite.

%t Table[If[n==1||n==3, 0, Select[FromDigits/@(Join[#,IntegerDigits[Prime[n]]]& /@ (Table[PadLeft[{4},k,4],{k,50}])),PrimeQ,1][[1]]],{n,35}] (* _Harvey P. Dale_, Feb 03 2011 *)

%Y Cf. A114783, A114784, A114785.

%K base,nonn

%O 1,2

%A _Amarnath Murthy_, Nov 17 2005

%E More terms from _Joshua Zucker_, May 06 2006

%E Edited by _Jon E. Schoenfield_, May 19 2019